[Stoves] Comments about T-LUDs

[Paul S. Anderson]

Dear A.D., Roger and all,

Interesting that both of you responded in terms of the fuels, but from 
different
perspectives.  Both mention the issue of the residual charcoal, so I 
start from
that point.

1.  It is OPTIONAL to save the charcoal, and AD makes a good case to do so in
India, and Roger mentions the benefits for the soils.  I prefer to save the
charcoal for several reasons:

    a.  If charcoal is burned under the full force of the fan, the heat is very
destructive to the fuel canister of the T-LUD.  However, if only a simmering
temperature is needed, low-air to the charcoal can give the right heat without
damaging the fuel canister.

    b.  The T-LUD is optimal for utilizing the pyrolytic gases (about 
80% of the
heat value) with very clean combustion.  But the T-LUD has not been 
shown to be
any better (and might be worse?) at burning charcoal with low emissions 
than is
the case with the dedicated charcoal burners.  So, save the charcoal 
and make it
into briquettes for use in the most appropriate charcoal burners.

    c.  In terms of the CDM for greenhouse gases, fossil fuels create more
greenhouse gases, burning biomass is net-neutral for CO2 if replanting occurs,
and only the T-LUDs can give the usable heat and still have a natural 
potential
to actually __reduce__ the greenhouse gases IF the charcoal is saved and
sequestered.  A family could generate a half tonne of charcoal from a year of
cooking with a T-LUD.  And that half tonne is equivalent to about 1.5 tonnes
(1500 kg) of CO2.  Even if credited with only one tonne of CO2 per household,
ten thousand households can yield 10,000 tonnes of improvement.  (Note: 
Compared to the corporations burning fossil fuels that do "buckets" of 
harm,
the T-LUDs in households can only do a few "drops" of benefits.)

2.  Roger wrote that: "maybe the biggest limitation of T-Luds is the
>> relatively modest energy conversion efficiency which limits the fuels we
>> can use in them."

T-LUDs have very high energy conversion (if I understand the term 
correctly), so
I think you are referring to not utilizing the energy of the charcoal.  
That is
a choice of the user.  If only 80% of the energy value of the switchgrass
pellets (or other fuels) is liberated, it remains the user's choice about the
other 20% that is in the charcoal.  But that 20% is not "lost" because of poor
energy conversion.

Also, the T-LUDs can probably use a greater variety of dry biomass than can
almost any other household-level combustion device.  Alexis Belonio 
openned our
eyes to the T-LUD ability to use rice husks.  Today I successfully burned rice
husks in a simple T-LUD (with forced air) that probably will cost less than
US$10 per combustion unit to manufacture (including the blower for $2 
available
from Vietnam)(but excluding the costs of the "stove structure" that holds the
pot and must look good in the kitchen).

Thank you for your comments thus far.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson



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